SOLUTION: Find the exact trig functions for sec(-11pie/12)

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Question 365005: Find the exact trig functions for sec(-11pie/12)
Found 2 solutions by CharlesG2, Alan3354:
Answer by CharlesG2(834) (Show Source):
You can put this solution on YOUR website!
Find the exact trig functions for sec(-11pie/12)

pi is spelled pi, not pie
sec((-11)/12)
sec = 1/cos
sec(-x)=sec(x)
cos(-x)=cos(x)
sec((-11)/12) = 1/cos((-11)/12)
sec((-11)/12) = sec((11)/12)
1/cos((-11)/12) = 1/cos((11)/12)

Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
sec(-11pie/12)
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I'll assume you meant the Greek letter pi, not the dessert, pie.
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sec(-11pi/12) = 1/cos(-11pi/12)
It's in the 3rd quadrant, so it's negative.
cos(-11pi/12) = -cos(pi/12)
cos(pi/6) = sqrt(3)/2
Use the half-angle formula to get cos(pi/12)
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cos(A/2) = � sqrt(1 + cos(A))/2